Wireless Connection Locks Up at Random

My problem has to do with my wireless networking connection suddenly and
without reason losing connection to the internet while still being connected
to the LAN, or at least SAYING it's connected to the LAN when in fact it has
completely locked up. On XP this was resolved 60% of the time by "repairing"
the connection. Other times that would cause the entire system to lock up, or
fail to do anything so the only way to get my connection back was to reboot
the computer. On Vista, you can't "repair" the same way you could in XP
(Vista diagnoses the problem and comes up with 3 solutions that are not the
problem and makes no attempt to repair). Manually disconnecting causes it to
lock up. A few times I have fixed it by unplugging my adapter and then
reconnecting it after a moment. I would try /release /renew but for some
reason it keeps telling me the action can not be performed when there is no
connection, even though it's connected with limited connectivity (in my
experience this just means the DHCP didn't assign the IP address correctly).
Rebooting is the ONLY way I can fix it for a while however, whenever I go to
reboot when the wireless NIC is locked up, it hangs at "logging off" until I
hard reset it, which I DO NOT LIKE TO DO! I have had hard drives critically
fail after a hard reset/power down, so I try to avoid doing it lest I
encounter a worst case scenario.

I have been having this problem since Windows XP, and I thought my worries
were over when I got Vista, because the problem has got to be Windows,
because even after I bought completely new components for my computer
(including 3 different Wireless NICs and 2 different routers) the problem
still occurs.